Uses equilibrium thermodynamics to predict the speciation of Cl and F in
volcanic gases and provide new estimates of the global emission rates to the
atmosphere. Calculations show that HCl and HF are the dominant species of Cl and
F in volcanic gases, at least several orders of magnitude more abundant than all
other species. Although large explosive eruptions are infrequent, they may
inject significant amounts of HCl and HF into the stratosphere.

Phosgene is one possible product from the oxidation of natural and
industrial chlorinated hydrocarbons which can further oxidize to form ClOx,
which destroys ozone. Measurements of phosgene show a mixing ratio of 17 pptv in
the upper troposphere and an average of 22 pptv in the lower stratosphere. These
values are substantially greater than those estimated with a model that only
considers the photochemical breakdown of CCl4, indicating the possible
significance of more reactive chlorocarbon compounds, especially CHCl3, CH3CCl3,
C2HCl3and C2Cl4 and their oxidation products in supplying chlorine to
the lower stratosphere.

Suspended particulate samples were collected weekly at three stations in the
Canadian Arctic between 1979 and 1984. Br concentrations peaked every year just
after the arctic dawn two orders of magnitude greater than could be explained by
marine, automotive, and crustal sources. Chlorine concentrations appeared to be
of marine origin. Iodine was found to be enriched relative to seawater by a
factor of 1000-10,000.

Global coverage by satellites of stratospheric trace constituents over long
time periods allows derivation of monthly zonal mean profiles. This has been
done for H, OH, HO2, H2O2, Cl, ClO, HCl, HOCl, ClONO2, NO and O. The standard
deviation of these quantities is a measure of their variability. Claims that
comparing theoretical variability estimates with measurements is a better test
of a photochemical theory than simply the comparison of single modeled and
observed profiles.

The response of tropospheric ozone to a change in solar UV penetration due
to perturbation of column ozone depends critically on the tropospheric NOx (NO +
NO2) concentration. At high NOx or a polluted area where there is a net ozone
production, a decrease in column ozone will increase the solar UV penetration to
the troposphere and thus increase the tropospheric ozone concentration. The
opposite would occur at remote oceanic areas where NOx is low. This may have
important implications for the interpretation of the long-term trend of
tropospheric ozone. Model calculations show that the change in OH, HO2 and H2O2
concentrations are independent of the NOx concentration.

In summer, atmospheric ozone was measured from an aircraft platform
simultaneously with nitric oxide (NO), oxides of nitrogen (NOy), and water vapor
over the Pacific Ocean in east Asia from 34° N to 19° N along the
longitude of 138 + or - 3° E. A good correlation in the smoothed meridional
distributions between ozone and NOy was seen. In particular, north of 25° N,
ozone and NOy mixing ratios were considerably higher than those observed in
tropical marine air south of 25° N.

Analysis of measurements leads to good agreement with recently published
results from the ATMOS/SL3 mission at 30° N latitude. The present research
represents an important step towards assessing the possibility of monitoring the
telluric ClONO2 column density from high mountain based stations.

The occurrence of bromo- and bromochloromethanes in marine air and seawater
of the Atlantic Ocean were measured and evaluated. A correlation exists between
high concentrations of these compounds in air and in water and the presence of
algae at the coastlines of various islands and high bioactivity in the Atlantic
Ocean near the West African coast.

N2O emission rates were measured during a 13-month period from July 1981 to
August 1982 at six different forest sites in Germany. The N2O emission rates
followed a general seasonal trend, with relatively high values during spring and
fall. There was a brief episode of relatively high N2O emission rates
immediately after thawing of the winter snow.

When the water was supersaturated with respect to atmospheric CO, H2, CH4,
and N2O, the transfer velocities of the emission process were smaller than those
determined for the deposition process. The results are interpreted by
destruction processes active within the surface microlayer.

The ozone profile was measured between 25 and 55 km by ground-based
millimeter-wave spectrometry from September 12 to October 29. Mixing ratio at 25
km decreased by 15% during the period, with no decrease observed at higher
altitudes, but considerable variability was found at all altitudes. The
observation that ozone depletion was confined to the lower stratosphere is
consistent with theories using heterogenous chemistry associated with polar
stratospheric clouds. This data did not support theories predicting depletion in
the upper stratosphere.

Balloon-borne high resolution thermal emission spectral data indicate the
ratio of total heavy isotopic ozone 50O3 to normal 48O3 shows enhancements of
about 45% at 37 km, decreasing to a minimum of about 13% at about 29 km, and
increasing to about 18% at 25 km. There is no accepted explanation for an
enhancement of stratospheric heavy ozone at this time.

Total vertical column amounts of HNO3 were measured in 1980 and 1986; while
NO and NO2 were also measured in 1986. The latter measurement defines for the
first time the ambient levels of these N species immediately following the
breakup of the polar vortex.

Presettlement vegetation in southern Wisconsin included areas of oak savanna
that supported an understory of prairie vegetation, as well as open prairie.
Estimates of N2O production by such systems could provide a base level to which
relative contributions from managed lands might be compared. Emissions were
monitored by a static chamber at three dissimilar sites. Emissions were similar
among the sites and very low, were not affected by wet periods, and were highest
with high soil temperatures and at spring thaw. Emissions were more than an
order of magnitude lower than reported from N-fertilized fields and generally
lower than from replanted forests.